Feed mechanism for grinding machine



March 21, 1967 E. R. DUNN FEED MECHANISM FOR GRINDING MACHINE 5Sheets-Sheet 1 Filed Aug. 19, 1964 INVENTOR ELM/1N 1?. DUNN ayZkMATTORNEY March 21, 1967 E. R. DUNN 3,309,820

FEED MECHANISM FOR GRINDING MACHINE Filed Aug. 19, 1964 5 Sheets-Sheet 21 L 1" i s x imi INVENTOR ELMAN R. DUNN ATTORNEY E. R. DU NN March 21,1967 FEED MECHANISM FOR GRINDING MACHINE 5 Sheets-Sheet 5 Filed Aug. 19,1964 l-h'llullllll lliL| INVENTOR ELMAN R- DUNN m ATTORNEY March 21,1967 E. R. DUNN 3,309,820

FEED MECHANISM FOR GRINDING MACHINE Filed Aug. 19, 1964 5 Sheets-SheetDEG FEES I 60 Z 00 E40 280 52 0 INVENTOR ELM/1N R.DUNN

i X g QLLJ TTORNEY March 21, 1967 E. R. DUNN 3,309,820

FEED MECHANISM FOR GRINDING MACHINE Filed Aug. 19, 1964 5 Sheets-Sheet 5LE]; 7 v L? INVENFOK ATTORNEY United States Patent 3,309,820 FEEDMECHANISM FOR GRINDING MACHINE Elman R. Dunn, Roscoe, 111., assignor toLandis Tool Company, Waynesboro, Pa. Filed Aug. 19, 1964, Ser. No.390,524 7 Claims. (Cl. 51165) This invention relates to feed mechanismfor grinding machines, particularly disc grinders, and moreparticularly, feed mechanisms of the type in which the feed movement isprovided by an electric stepping motor.

Stepping motors are constructed in such a manner that upon beingenergized, the motor will turn only through a predetermined part of arevolution. When a stepping motor is used as a means for feeding agrinding wheel support, it is desirable to provide for rotating themotor by a single step, by a predetermined number of steps, or to rotatethe motor by a rapid series of steps to ad- Vance or to retract thewheel support through a predetermined distance. Ordinarily, to be ableto operate a stepping motor in this manner would require a large blockof relays, timers and other electrical control elements.

It is, therefore, an object of the present invention to provide arelatively simple control device for operating a stepping motor typefeed mechanism to provide bidirectional feed increments in the form of arapid succession of increments, a pre-selectcd number of increments or asingle increment.

Another object is to provide a stepping switch and means for actuatingthe same in accordance with various requirements of a feed mechanism.

Another object is to provide a dual stepping switch for controlling thebi-directional feeding of both discs of a double disc grinder toward andfrom grinding position.

Another object is to provide means for actuating said switchcontinuously or by increments.

FIG. 1 is a front elevation of the stepping switch.

FIG. 2 is a plan view of the stepping switch.

FIG. 3 is an end elevation of the stepping switch.

FIG. 4 is an electric circuit.

FIG. 5 is a chart showing the sequence of operation of switches 1, 2, 3and 4.

FIG. 6 is an end elevation of a disc grinder.

The grinding machine to which the invention is applied consists of a bed50 having a pair of slides 51 movable longitudinally thereon. Only oneslide is shown. Each slide has an abrasive disc 52 rotatably mountedtheron. A feed screw 53 is rotatably mounted in bed 5% and is inoperative engagement with a nut 54 on slide 51.

The means for rotating eed screw 53 consists of a worm wheel 55 monutedthereon in engagement with a worm 56 on shaft 57. Shaft 57 is rotatablysupported in bed 59. A hand wheel 58 is attached to one end of shaft 57for manual operation of feed screw 53. A stepping motor 9MTR is attachedto the other end of shaft 57 for power operation of the feed screw 53.

The feed mechanism for each disc is actuated by a stepping motor. Thestepping motor may be controlled to advance or retract the feed by asingle increment, by a predetermined number of increments or by a rapidsuccession of increments.

The means for controlling said stepping motor 9MTR consists of a set ofcam operated switches 1, 2, 3 and 4 for each motor. The rest of thedescription is directed to one set of switches. It is to be understoodthat the term switch as used here includes all well known devices whichperform the function of a switch including solid state devices.

Three of the switches 1, 2 and 3 are connected in the circuit to astepping motor 9MTR. Only two of these Patented Mar. 21, 1967 switchesare closed at any one time. The fourth switch closes for each incrementregardless of which of the first three switches is closed. Thiscombination of switches may be referred to as a stepping switch.

Cams 5, 6, 7 and 8, for actuating switches 1, 2, 3 and 4, are mounted onshaft 9 in predetermined angular relation, and located in said relationby pin 40 passing through locating holes in said cams. The cams arepinned to shaft 9 and pin 40 is removed. The cams may be rotatedcontinuously in either direction by an electric motor 10. When operatedin this manner, the stepping motor and feed mechanism are actuated in arapid succession of increments in either direction. The cams may also berotated intermittently by ratchet mechanism 11 actuated by solenoid 30.Solenoid 39 may be actuated by push button FBI and counter relay ZCTR,to provid a single increment or a predetermined number of increments.

Switches 1, 2, 3 and 4 are supported in a frame 12, one end of which ispivotally supported at 13 on base member 20, the other end of which isresiliently supported by fiat springs 14 which permit a certain amountof arcuate movement of frame 20 about pivot 13 in either direction.Spring plunger screws 21 and 22 stabilize frame 12 in its central orneutral position as shown.

On the end of shaft 9 adjacent springs 14 is a traction member 15. Whenit is desired to provide a rapid succession of increments of feed ineither direction, frame 12 and switches 1, 2, 3 and 4, along withtraction member 15, are swung about pivot 13 by means of solenoid 16.Solenoid 17 swings the right hand frame to feed the right hand disc.

Traction member 15 is thus moved into frictional engagement with one oftwo continuously driving members 18 or 19 driven by motor 10 to rotateshaft 9 and earns 5, 6, 7 and 8 in either direction, depending onwhether the feed movement is for advancing or retracting the grindingdiscs.

The controls for actuating the stepping motor to retract the grindingwheel are similar to those described above for operating said motor toadvance the grinding wheel, except that, obviously, reverse direction ofrotation of the camshaft is effected through energization of theappropriate solenoids.

OPERATION Normal increment feed To initiate normal or ratchet operatedincrement feed, push button P131 is closed momentarily to energize relay9CR.

Relay contact 9CR1 closes in a circuit with normally closed contact 7CR1and counter contact 2CTR3 to hold relay 9CR after push button FBI isreleased.

Relay contact SCRZ closes to complete a circuit through motor controlrelay 9MCR and to counter relay ZCTR.

The 9MCR contacts close in the circuit to stepping motor 9MTR. Saidstepping switch actuates the feed screw 53 in nut 54 to provide apredetermined feed increment for the abrasive disc 52.

Counter relay ZCTR may be set for a predetermined number of incrementsor steps.

Counter contact ZCTRS completes the holding circuit to relay 9CR.

Counter contact ZCTRZ completes a circuit to energize solenoid 3t} andcounter relay 2CTR.

Solenoid 30 actuates pawl 31 to turn ratchet 11 and cams 5, 6, 7 and 8one increment.

Energization of solenoid 3i) will be repeated by suitable controlelements if the counter is set for more than one increment.

When a single step or a predetermined number of steps is completed,counter relay 2CTR is deenergized through complete count-out.

Counter contact 2CTR2 opens to deenergize solenoid 30 to permitresetting pawl 31 actuated by solenoid 30.

Counter contact 2CTR3 opens to deenergize relay CR and stepping motor9MTR, and the counter is reset to zero for the next count.

Repealing increment feed If it is desired to provide a continuousincrement feed by continuous rotation of shaft 9, the increment feedselector switch A is set to close a circuit to energize motor and relay7CR.

Push button FBI is depressed and held to complete a circuit to energizerelay 9CR.

Relay contact 9CR1 closes in a circuit from contact 7CR2 throughnormally open limit switch 4 to relay 9CR as indicated above, switch 4closes for each increment.

Relay contact 9CR2 closes in a circuit to energize relay 9MCR andstepping motor 9MTR.

Relay contact 9CR3 closes in a circuit from contact 7CR4 to energizesolenoid 16 and swing frame 12 and traction member into engagement withdriving member 18 to effect continuous rotation of shaft 9.

With any two of the contacts MCSl, MCSZ or MCS3 closed, the motor turnsthrough a single increment or step.

Successive steps will occur as the combination of contacts 1, 2 and 3 ischanged by rotation of the corresponding cams.

Continuous rotation of cams 5, 6, 7 and 8 by motor 10 causes opening andclosing of contacts 1, 2 and 3 in a predetermined sequence to providesuccessive steps or increments of rotation of motor 9MTR in eitherdirection depending on the direction of rotation of said cams, until anabrasive disc 52 is advanced rapidly to the desired position.

The sequence of contact operation is illustrated in the chart, FIG. 5.

Push button FBI is released to stop the feed movement with the disc inthe desired position.

Relay 9CR is deenergized upon release of push button PBl, unless, atthat moment, contact MCS4 is held closed by cam 8, in which event,camshaft rotation continues until cam 8 permits contact MCS4 to open anddeenergize relay 9CR, and thus prevent stopping rotation of shaft 9 withthe pins on ratchet mechanism 11 in improper position relative to pawl31.

Relay contact 9CR2 opens to deenergize relay 9MCR and stepping motor9MTR.

Relay contact 9CR3 opens to deenergize solenoid 16, permitting springplunger screw 22 to swing frame 12 about its pivot 13 and disengagetraction member 15 from driving member 18 to stop rotation of shaft 9and the cams mounted thereon.

1 claim:

1. In a grinding machine having (a) a feed mechanism for advancing andretracting a grinding wheel,

(b) means for actuating said feed mechanism comprising (c) a steppingmotor,

(d) means for controlling said stepping motor comprising (e) a steppingswitch mechanism having a plurality of switches,

(f) a corresponding plurality of rotatable cams for actuating saidswitches,

( g) means for rotating said cams continuously in either direction toactuate said feed mechanism in a rapid serie of c eme t (11) means toengage and disengage said cams from said continuous rotating means,

(i) a ratchet mechanism for rotating said cams intermittently,

(j) means to actuate said ratchet mechanism and said cams to provide asingle increment of feed or a predetermined number of increments.

2. In a grinding machine having (a) a feed mechanism for advancing andretracting a grinding wheel,

(b) means for actuating said feed mechanism comprising (c) a steppingmotor,

((1) means for controlling said stepping motor comprising (e) a steppingswitch mechanism having a plurality of switches and a correspondingplurality of rotatable cams for actuating said switches.

31 In a grinding machine having (a) a feed mechanism for advancing andretracting a grinding wheel,

(b) means for actuating said feed mechanism comprising (c) a steppingmotor,

(d) means for controlling said stepping motor comprising (e) a steppingswitch mechanism having a plurality of switches,

(f) and means for actuating said switches in a predetermined sequencecomprising a corresponding plurality of rotatable cams.

4. In a grinding machine having (a) a feed mechanism for advancing andretracting a grinding wheel,

(b) means for actuating said feed mechanism comprising (c) a steppingmotor,

(d) means for controlling said stepping motor comprising (e) a steppingswitch mechanism having a plurality of switches and a correspondingplurality of rotatable cams,

(f) and means for rotating said cams continuously to actuate said feedmechanism in a rapid series of increments.

5. In a grinding machine having (a) a feed mechanism for advancing andretracting a grinding wheel,

(b) means for actuating said feed mechanism comprising (c) a steppingmotor,

(d) means for control-ling said stepping motor comprising (e) a steppingswitch mechanism having a plurality of switches and a correspondingplurality of rotatable cams,

(f) means for rotating said cams continuously to actuate said feedmechanism in a rapid series of increments,

(g) and means to engage and disengage said cams from said continuousrotating means.

. In a machine tool having movable elements,

(a) means for actuating one or more of said elements comprising (b) astepping motor,

(c) a plurality of switches for actuating said motor,

(d) means for actuating said switches in a predetermined sequence torotate said motor intermittently,

(e) means for operating said actuating means continuously to rotate saidmotor through a continuous series of steps,

(f) and means to operate said actuating means to rotate said motorthrough a predetermined number of steps or a single step.

6 7. In a machine tool having movable elements, (f) and counting meansto operate said actuating means (a) means for actuating one or more ofsaid elements to rotate said motor through a predetermined numbercomprising of steps or a single step. (b) a stepping motor, (c) aplurality of switches for actuating said motor, 5 References Clted bythe Exammer (d) means for actuating said switches in a predeter- UNITEDSTATES PATENTS mined sequence to rotate said motor intermittently1,978,110 10/1934. Keams Comprising a plurality of calm, 2 334 531 111943 p 51 1 55 (e) means for operating said actuating means con-2,881,568 4/1959 Hahn et a1 51 165 X tinuously to rotate said motorthrough a continuous 10 series of steps, LESTER M. SWINGLE, PrimaryExaminer.

1. IN A GRINDING MACHINE HAVING (A) A FEED MECHANISM FOR ADVANCING ANDRETRACTING A GRINDING WHEEL, (B) MEANS FOR ACTUATING SAID FEED MECHANISMCOMPRISING (C) A STEPPING MOTOR, (D) MEANS FOR CONTROLLING SAID STEPPINGMOTOR COMPRISING (E) A STEPPING SWITCH MECHANISM HAVING A PLURALITY OFSWITCHES, (F) A CORRESPONDING PLURALITY OF ROTATABLE CAMS FOR ACTUATINGSAID SWITCHES, (G) MEANS FOR ROTATING SAID CAMS CONTINUOUSLY IN EITHERDIRECTION TO ACTUATE SAID FEED MECHANISM IN A RAPID SERIES OFINCREMENTS, (H) MEANS TO ENGAGE AND DISENGAGE SAID CAMS FROM SAIDCONTINUOUS ROTATING MEANS, (I) A RATCHET MECHANISM FOR ROTATING SAIDCAMS INTERMITTENTLY, (J) MEANS TO ACTUATE SAID RATCHET MECHANISM ANDSAID CAMS TO PROVIDE A SINGLE INCREMENT OF FEED OR A PREDETERMINEDNUMBER OF INCREMENTS.